chucka and Bmac,
I wanted to thank you both for your kind words. I don't stop by this board near as often as I should.
This project, which is ongoing, is worth every penny and second. The time spent with my kids alone makes it worth it, and the looks I get as we cruise past the 1/4 million dollar yachts on our lake is just icing on the cake.
You really have two approaches to how you strip and refinish. Chemicals and elbow grease.
What we did was use chemicals on anything we could that was removable, and able to be tabled in the driveway where we could control run-off. Everything else was done with a good quality woodworking scraper that you get at any hardware store. Buy lotsa blades, unless you can resharpen them. I never had much luck with that, but we did the whole boat with about 20. Round the cutting corners slightly with a file so you don't dig in, and take your time.
About the black lines. They are caulking similar to what you're used to working with, and will pull out if you get too aggresive. It'll take you a while to get the hang of it, but once you do, it goes pretty well. If you come across some loose sections, you can cut out what's loose, and patch in new caulking. Mask around the area very carefully, because you cannot remove the caulking from the grain, or sand it off after to get it flush. I'm not sure what type we used, but a little research will get you the right kind for deck seams.
If you have any finish left in another spot, use this as your guideline as to what you put on. Consider adding a UV inhibitor and some non-slip grit to the last couple coats, and you're in like Flynn!
I can't stress Honey Teak enough, that stuff is bullet proof. Takes a little getting used to, 'cause you have to mix each batch and apply it all before it hardens, but you can snuff a cigarette out on the cured stuff without a blemish, and touch-up is a breeze.
Hope I helped, and sorry for the late reply.